多波段共孔径离轴三反光学系统设计

Design of multi-band off-axis three-mirror optical system with common aperture

针对军用光电系统对视场范围、图像质量和系统小型化的迫切需求,根据指标要求设计了一种大口径离轴三反光学系统。采用离轴多反式结构消除系统遮拦,缩减结构尺寸,通过引入复杂面型实现大孔径设计,在保证足够分辨率的同时,增大光学系统的视场角,以获得更加丰富的目标特征,提高了系统的目标探测和识别能力。与透射式结构与折返式结构相比,大幅度减小了光电产品的体积和质量,有效减轻了伺服设计负荷,具备隐蔽性好、光谱覆盖范围广、透过率高、视场兼容性强的特点。设计结果表明:电视光路在120 lp/mm处全视场MTF>0.2,短波红外光路在60 lp/mm处全视场MTF>0.3,中波红外在30 lp/mm处全视场MTF>0.15,网格畸变小于0.5%,满足设计指标要求。

Aiming at the urgent requirements of military photoelectric system for field of view,image quality and system miniaturization,a large-aperture off-axis three-mirror optical system was designed according to the index requirements.The off-axis multi-mirror structure was adopted to eliminate the system obstruction and reduce the structure size.By introducing the complex profiles,the large-aperture design was realized.While ensuring the sufficient resolution,the field of view angle of the optical system was increased to obtain richer target features and improve the target detection and recognition ability of the system.Compared with transmission-type structure and foldback system,it greatly reduced the volume and weight of photoelectric products and effectively reduced the load of servo design,which had the characteristics of good concealment,wide spectrum coverage,high transmittance and strong field of view compatibility.According to the design results,the full field of view modulation transfer function(MTF)of TV optical path is higher than 0.2 at 120 lp/mm,the MTF of SWIR optical path is higher than 0.3 at 60 lp/mm,the MTF of MWIR optical path is higher than 0.15 at 30 lp/mm,and the grid distortion is less than 0.5%,which meet the design index requirements.